368 NEW DEVELOPMENTS IN THE 700 WORLD

l r l t ZOO kb. (1989) 28: 26X-271 6 The Zoological Society of London

A mealworm dispenser for the Slender-tailed meerkat

at London Zoo Surica t(i suricat tu

DAVID SHEPHERDSON', TRACY BROWNBACK' & ANN JAMES2

London, Regent's Park, London NWI 4 R Y , Great Britain Curators' Research Group and 2Small Mammal Keeper, The Zoological Society of

Few people would deny that naturalistic enclosures which encourage natural beha- viour patterns are desirable both for the animals and the viewing public. Animals displaying natural behaviour patterns are more interesting and educational (Sommer, 1972; Coe, 1985; Maple & Finlay, 1987) and their welfare is likely to be superior (Hutchins er al., 1984).

However, such enclosures will only be successful if they are naturalistic from the animal's point of view. No animal inter- acts with or is even aware of all parts of its environment. Some features will be more significant than others and if natural behaviour is desired i t is these that must be recreated in captivity.

Most behaviours are 'goal directed', for example. an animal may dig in order to build a burrow or hunt in order to satisfy its hunger. Since the survival of most wild animals relies on successful execution of these behaviours, there are good evolu- tionary grounds for believing that they may provide the animal with some form of a rewarding experience. In the termino- logy of psychology these behaviours are appetitive. An environment that does not allow for a full range of natural beha- viours will at the very least deprive an animal of a source of positive stimulation and at worst may be a source of frustra- tion (van Hoof, 1986).

When they are not sleeping or resting most wild animals spend a large amount of time engaged in feeding-related activi- ties. Providing for a full range of foraging behaviour therefore may be one of the

most important aspects of a captive environment.

The project described here was an attempt to provide an environment for a group of Slender-tailed meerkats Suricata suricatta in which foraging behaviour is rewarded with discovery of food items. An important feature is that, as in the wild, the availability of the food source is unpredictable. It was also a consideration that the device used was simple to make and easy to maintain. Several attempts to enrich environment by the provision of prey have been made (Foster-Turley & Markowitz, 1982; Markowitz. 1982; Cher- fas, 1984) but most have been somewhat sophisticated (electro-mechanical devices with microcomputer control) and conse- quently expensive and difficult to main- tain. Environmental enrichment that relies on large amounts of money and keeper time will not be practicable in many cases.

ENCLOSURE The meerkats, an adult pair and 2.1 juve- niles, were housed in the Clore Pavilion for Mammals in a glass-fronted enclosure measuring 3 x 2 x 2 m with a skylight. A door in the rear wall connected the enclo- sure to a service passage. The enclosure was furnished with several large logs and branches, two piles of stones, one of which concealed the nestbox, and a sand substrate 6cm deep.

The normal daily diet was composed of 90% meat, with a vitamin/mineral supple- ment, presented at around midday. This

NEW DEVELOPMENTS IN THE ZOO W O R L D 269

Fig. 1. Mealworm dispenser used in Slender-tailed meerkat Suricata suricatta enclosure.

was supplied throughout the study. Meal- worms Tenebrio molitor when offered were additional to the normal diet.

MATERIALS The mealworm dispenser consisted of a 50cm length of 5cm diameter perspex/ Plexiglas tubing. The open ends were covered with removable end caps and ten 6mm holes were drilled along one side (Fig. 1). The tube was filled with a mixture of 25-30 mealworms (for culturing methods and nutritional analysis see Martin et al., 1976) and sawdust, and was fixed to the roof of the enclosure with a steel tool clip. As the mealworms moved around within the tube they would even- tually fall onto the sand substrate beneath and it would take about eight hours for c.30 mealworms to ‘dispense’ themselves. The effect of the dispenser could be increased by providing clips at several points so that its position could be varied from day to day and/or by mounting it over a complex substrate, such as a pile of rocks or logs, causing the mealworms to be scattered and hidden.

BEHAVIOURAL OBSERVATIONS The meerkats were observed on 12 days over a period of four months. On six observation days the dispenser was opera- tional (full of mealworms), the other six it

was not. Mealworms were available on approximately half of the non-observa- tion days. The behaviour of the whole group was recorded for 30 minutes five times per day at regular intervals between 1000 and 1600 hours using an instanta- neous scan sampling technique (Martin & Bateson, 1986) with an inter-scan interval of 30 seconds. The following exclusive behavioural categories were identified: digging/foraging = a scratching motion with a foreleg on the ground or an object; locomotion = any movement from one part of the cage to another; sit/stand = stationary; sleep; pacing = regular and repeated locomotion along the same path at the glass front of the enclosure; social interaction = including short periods of fighting, chasing and mutual grooming; look-out = standing on hind legs and staring intently; hidden = out of sight from public area; other = all behaviours not otherwise ca tegorised.

The scan samples were used to calculate the daily group activity budget. Behaviour on days when mealworms were and were not available were compared using a Mann-Whitney U-test and correlations were assessed using the Spearman Rank Correlation Coefficient.

RESULTS Figure2 shows the amount of daily time occupied by the group in the various behavioural categories when mealworms were and were not present.

The change in behaviour as a conse- quence of mealworm availability is seen more clearly in Fig. 3 . For each category the height of the bar was calculated by subtracting the percentage of time occu- pied by a behaviour when mealworms were not present from the percentage of time occupied when they were. The grea- test effect is an increase in the amount of time spent digging/foraging from 9.1 % to 329% (U = 0, P < 0.002). This is corre- lated with a decrease in the amount of time spent stationary from 374% to 17.4% (U = 0, P < 0002). This negative correlation is significant (Rs = -086,

270

% vis ib le obs. time

35-

25-

15-

5-

A

a b C d

NEW DEVELOPMENTS IN THE ZOO WORLD

mealworms 0 no mealworms

1

IL e f 9 h i

Fig. 2. Daily activity budget of meerkat group with (solid bars) and without (open bars) mealworms in the dispenser. a. digging/foraging; b. locomotion; c. sit/stand. d. sleep; e. pacing; f. social interaction; g. lookout; h. other; i. hidden.

P < 0.01 ). The meerkats also spent signifi- cantly more time visible to the public when mealwornis were present being hidden for only 3% of observation time as opposed to 5.8% of the time when meal- worms were not present (U = 4. P < 0.026).

Other changes which were observed, but which did not reach significance level, were an increase in locomotion and a

+ 4 0 1

- 4 0 1 Fig. 3. Change in the daily activity budget of the meerkats in the mealworm dispenser experiment. Plus = YO behaviour with mealworms present. Minus = % hehaviour in the absence of mealworms. a. digging/ foraging; b. locomotion; c. lookout; d. sit/stand; e. sleep; f. social interaction; g. pacing; h. other.

decrease in sleeping, social interaction and pacing. A study is in progress to establish the cause of the latter behaviour.

Overall the meerkats spent more time in view, digging/foraging and moving about when the mealworm dispenser was being used. Although data were not collected it was the observer’s impression that digging was increased throughout the enclosure, not just in the area under the dispenser where the worms were falling. There was no evidence from the data that the dispenser had become less effective with time over the four months of the study.

Field data currently being analysed by D. W. Macdonald (pers. comm.) suggest that wild meerkats spend some 37% of their day digging for food. Thus the meal- worm dispenser seems to have induced a behaviour pattern that is more similar to that seen in the wild than was the case previously.

DISCUSSION This study shows how an addition to a naturalistic exhibit of a key characteristic of the natural environment, namely the opportunity to forage for and obtain

NEW DEVELOPMENTS I N T H E ZOO WORLD 27 1

food, can result in more natural beha- viour patterns. This occurred despite the fact that mealworms were supplied in addition to the normal diet; the animals did not have to forage in order to obtain their daily food requirement. Not only were they more active but they were also visible to the visiting public for a greater part of the day providing a more inter- esting and educational exhibit.

The device is cheap, easy to make and requires little time either to fill or to install, yet i t provides a form of environ- mental enrichment for a significant proportion of the day.

This approach could be used with many of the small insectivorous mammals frequently exhibited in zoos with benefits for both animals and zoo visitors.

ACKNOWLEDGEMENTS

This project was conducted as part of a project on Behavioural Enrichment supported by The Zoological Society of London and the Universities’ Federation for Animal Welfare. We would like to thank Peter Olney, Curator of Birds and Reptiles, Jo Gipps, Curator of Mammals, Peter Rodway, Head Keeper and the Keepers of the Charles Clore Pavilion for Mammals for their help and encouragement.

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occupancy evaluation in the zoo. Appl. Anini. Beh. Sci. 18: 5-18. MARKOWITZ, H. (1982): Behavioral enrichment in the zoo. New York, London: Van Nostrand Reinhold. MARTIN. P. & BATESON, P. (1986): Measuring behaviour. Cambridge: Cambridge University Press. MARTIN. R. D.. RIVERS, J. P. W. & C o w c u , U. M. (1976): Culturing mealworms as food for animals in captivity. In ! . Zoo Yb. 16 63-70. SOMMER, R. (1972): What do we learn at the zoo? Nar. Hist. 81(7): 2627, 84-85. VAN HOOF, J. A. R. A. M. (1986): Behavior requirements for self-sustaining primate popula- tions: some theoretical considerations and a closer look at social behavior. In Priniates: the road io selfi sustaining populaiions: 307-329. Benirschke, K . (Ed.). New York: Springer-Verlag.

MAPLE, T. L. & FINLAY, T. W. (1987): Post-

Manuscript submitted 13 December 1988